Method for loosening frozen ore beds



May 4, 1965 w. FFWURZBURG ETAL 3,181,799

METHOD FOR LOOSENING FROZEN ORE BEDS Filed Sept. 6, 1962 a sis W [Ya/697L575; [JarrenFZZ/u 136w" MB BY Jae/Z United States Patent 3,181,799 METHOD FOR LOOSENING FROZEN ORE BEDS Warren F. Wurzburg, Wheaton, and Jack M. Reid, Villa Park, Ill., assignors, by mesne assignments, to Goodman Manufacturing Company, Chicago, 11]., a corporation of Illinois Filed Sept. 6, 1962, Ser. No. 221,802 6 Claims. (Cl. 2411) Our present invention relates to a method for effectively separating lumps of ore, such as coal, and other granular materials which have become bound together with ice.

It is a customary practice to wash ore, such as coal, with water at the mine site prior to delivery of the coal for transportation therefrom. During periods of low ambient temperature, the residual surface moisture on the lumps of coal may freeze causing the coal lumps to adhere solidly together with ice. When this occurs during shipment of the coal in railway cars, trucks or barges, or during storage in bins, unloading of the coal from the shipping vehicle or storage container and handling for subsequent use is greatly hampered. The present practice of loosening a bed of coal thusly bound with ice is either to thaw the ice by application of heating devices or to break apart the coal lumps mechanically by means of low-frequency shakers. These methods .are slow, cumbersome and lessthan completely effective. Under certain conditions with the presently used methods and in some suggested methods that involve the application of high mechanical forces to break apart the frozen coal lumps, the coal lumps are broken into smaller size particles which is often undesirable for the intended end use of the coal. Likewise, it has been found, that antifreeze agents added to the Wash water or appliedto the coal after washing are not completely effective in preventing the adhering of coal lumps by the freezing of surface moisture.

it is an object of our present invention to effectively separate lumps of ore, such as coal, which have become bound together with ice so as to make them free flowing and easily handled during conventional unloading and conveying operations.

it is another object of our present invention to separate essentially instantaneously lumps of ore, such as coal, which have been bound together with ice While in large transport or storage containers even when the ambient temperatures are below freezing.

It is a further object of our present invention to effect separation of lumps of ore, such as coal, that have become bound together with ice, without reducing the original size of the ore lumps.

in accomplishing the foregoing objects, we propose to effect immediate separation of ore lumps, which have been bound together by frozen surface moisture, by the applica'- tion of high-intensity vibrational energy of selected wavelength characteristics. The application of vibrational energy of this nature to the frozen glomerate of oreand ice serves to destroy the ice bonds, thereby freeing and separating the individual lumps of, ore.

Now, in order to acquaint those sldlled in the art with the manner of using methods in accordance with theprinciples of our present invention, we shall describe in connection with the accompanying drawing, a preferred embodiment of our invent-ion.

In the drawing:

FIGURE 1 is a fragmentary view of a bed of coal com prising individual coal lumps bound together with ice;

FIGURE 2 is a schematic view of-one embodiment of our present invention as applied to a conventional railway coal car shown in longitudinal section;

- by frozen surface moisture.

GURE 3 is a median longitudinal sectional View of a transducer suitable for carrying out the method of our present invention; and

FIGURE 4 is a transverse sectional view, taken substantially along the line 44 in FIGURE 3, looking in I the direction indicted by the arrows.

Referring now to the drawing, there is shown in FIG- UPlE 1 a fragmentary View of a bed of ore, such as coal, indicated generally by the reference numeral 10, comprising individual coal lumps 11 which are joined at points of mutual contact by ice bonds 12. To effect separation of the individual coal lumps 11 in accordance with the principles of our present invention, we propose to apply high-intensity vibrational energy to the frozen glomerate of coal and ice which will cause oscillatory forces to be set up within the bed Some of the oscillatory force created by the application of vibrational energy will tend to shear the ice bonds joining the individual lumps of coal. This effect may be negligible in certain instances as some of the applied energy may be absorbed by the molecular structure of the coal or lost as heat. If the Wavelength of the applied vibrational energy is properly selected, however, a resonant condition will exist which will result in extremely high shear forces Within the ice bonds. These forces will tend to shatter the ice bonds, thereby separating the individual lumps of coal. As long as the bonds of ice are intact, the vibrational energy is transmitted easily throughout the glomerate. However, when a bond is broken and an individual lump is freed from the rest, the energy is no longer easily transmitted to that lump. The applied energy is then concentrated in the bonds that remain intact, increasing the: shear forces until failure occurs. The kinetic energy of oscillatory w motion is eventually dissipated as heat energy. At wavelengths wherein a resonant condition is established which concentrates the oscillatory forces within the. ice bonds, this heat is also dissipated primarily in thelocal region of the ice bonds. The resulting rise in temperature at this point is also helpful in destroying the ice bonds.

One application o-f these principles is illustrated in FIGURE 2 wherein there is shown a conventional railway coal'car 13 loaded with a bed of coal 10 comprising washed lumps of coal 1-]. that have been agglomerated In this condition, the coal 11 will not flow through the unloading openings it provided at the bottom of the car 13. In. practicing our present invention, suitable means are provided for generating a high-intensity vibrationalwave of the required frequency. Such means preferably comprises a high-voltage D.-C. electrical current source 15, an electrical capacitor 16, and a transducer 17 in contact, direc ly or indirectly, with the bed of frozen coal. 10.

tangular retaining ring 21 secured to the adjacent walls ciently converting electrical energy stored in the capacitor 16 to a vibrational wave of the desired frequency and adequate intensity is shown in FIGURES 3 and 4. The transducer 17 comprises a rectangular body member'ld having a lengthwise extending generallysemi-cylindrical cavity 19 formed therein which is open at the bottom side thereof as'viewed in FIGURES 3 and 4. The open face of the body member 18 is closed by a thin flexible diaphragm 2% that is held in position by a suitablerrecof the body member 18 by means of a plurality of machine screws 22. The curved surface of the cavity 19 serves as a reflector for a purpose to be more fully disclosed hereinafter. The body member 18 and diaphragm 20 serve to define an enclosed hollow housing which is filled with a suitable nonflammable antifreeze liquid 23. Extending through the opposite end walls of the body member 18 and projecting into the liquid 23 are a pair of axially aligned electrodes 24 suitably separated from the end walls by tubular electrical insulators 25.

The transducer 17 is attached to the frozen coal bed in a manner so that efficient coupling is achieved for transmission of a vibrational wave to the coal bed. As shown in solid lines in FIGURE 2, the transducer may be attached to the exterior of the steel shell from which the railroad car 13 is constructed so as to become an integral part thereof. Alternatively, as shown in dot-dash lines, the transducer 17 may be placed in firm contact with the surface of the frozen coal bed 10 by the action of a hydraulic cylinder or other suitable mechanical means (not shown). In either case, the transducer 17 is positioned with the diaphragm 24 facing the coal bed 19.

In the electrical circuit for the afore-described current source 15, capacitor 16 and transducer 17, the one terminal 26 of the capacitor 16 is connected through conducting means 27 to the terminal 28 of the current source and to one of the electrodes 24 of the transducer 17; and the other terminal 29 of the capacitor 16 is connected through conducting means 30 to the terminal 31 of an electrical switch 32 and to the terminal 33 of an electrical switch 34. The terminal 35 of the switch 32 is, in turn, connected through a conductor 36 to the terminal 37 of the current source 15, and the terminal 38 of the switch 34 is connected through a conductor 39 to the other of the electrodes 24 of the transducer 17.

In operation, the capacitor 16 is first charged by closing the switch 32, While the switch 34 remains open, whereupon current flows between the current source 15 and the capacitor 16 through the conducting means 2.7 and 30, switch 32 and conductor 36. When the capacitor 16 is fully charged, the switch 32 is open and the switch 34 is closed which allows the electrical charge stored in the capacitor 16 to be discharged rapidly to the electrodes 24 of the transducer 17 through the conducting means 27 and 30, switch 34 and conductor 39. As the capacitor 16 is thus discharged, a spark is created between the electrodes 24. The passage of current through the liquid 23 in the gap between the electrodes 24 causes a plasma to be formed for the duration of the spark. The forma tion of this plasma and subsequent decay of the plasma when the capacitor 16 is discharged causes a shock wave to be set up in the enclosed liquid 23. This wave is focused and reflected, by the curved surface of the cavity 19, through the liquid 23 to the flexible diaphragm where it is transmit-ted to the coal bed 1% as a high-intensity vibrational Wave. The vibrational wave causes oscillatory forces to be set up within the coal bed 10 which serve to break the ice bonds, thereby freeing and separating the individual coal lumps 11.

The wavelength of vibrational energy required for most efficient separation of coal lumps is a function of the size of the lumps and of the physical properties of the coal and ice at the existing temperature. Ordinarily, the wavelength of the vibrational Wave should be approximately equal to the average dimension of the individual coal lumps for most satisfactory results. The wavelength of the vibrational wave produced by the transducer is a function of the electrode spacing and position in the housing, and of the characteristics of the electrical circuit. These variables canbe selected by those skilled in the art to provide the required rise and decay time of the plasma to produce a vibration wave with the desired wavelength.

From the foregoing description, it will be apparent that we have provided a new and novel method for effectively, and essentially instantaneously, separating lumps of coal which have become bound together with ice so as to make them free flowing for easy handling, without reducing the original size of the coal lumps. As will also be apparent, the method of our present invention is adapted for separating frozen coal lumps while in large transport or storage containers. Moreover, as will be recognized by those skilled in the art, the method of our present invention may be used for separating lumps or particles of other types of ore and granular materials which have become bound together with ice.

While we have shown and described what we believe to be a preferred embodiment of the method of our present invention, it will be understood by those skilled in the art that various arrangements and modifications may be made therein without departing from the spirit and scope of our invention.

We claim:

1. A method for separating lumps of coal which have become joined together by ice bonds in a frozen glomerate comprising the step of applying to the glornerate for fracturing the ice bonds therein a high-intensity vibrational energy in the range of 0.1 to l joule per pound of coal in the glomerate.

2. A method for separating lumps of coal which have become joined together by ice bonds in a frozen glomerate comprising the step of applying to the glomerate for fracturing the ice bonds therein a high-intensity vibrational wave with a Wavelength approximately equal to the average dimension of the individual lumps of coal.

3. A method for separating lumps of ore which have become joined together by ice bonds in a frozen glomerate comprising the steps of creating an electrical charge, discharging the electrical charge within a liquid maintained separate from the glomerate for establishing a shock wave therein, and transmitting the shock wave as a vibrational wave to the glomerate for fracturing the ice bonds.

4. A method for separating lumps of ore which have become joined together by ice bonds in a frozen glomerate comprising the steps of creating an electrical charge, discharging the electrical charge within a nonfiammable antifreeze liquid maintained separate from the glomerate for establishing a shock wave therein, and transmitting the shock wave as a high-intensity vibrational wave to the glomerate for fracturing the ice bonds.

5. A method for separating lumps of ore which have become joined together by ice bonds in a frozen glomerate comprising the steps of establishing a shock wave within a liquid maintained from the glomerate, and permitting the shock wave to be transmitted as a vibrational wave to the glomerate for fracturing the ice bonds.

6. A method for separating lumps of coal which have become joined together by ice bonds in a frozen glomerate comprising the step of applying to the glomerate for fracturing the ice bonds therein high-intensity vibrational energy in the range of 0.1 to 1 joule per pound of coal in the glomerate and with a wavelength approximately equal to the average dimension of the individual lumps of coal.

References Cited by the Examiner UNITED STATES PATENTS 2,078,933 5/37 Dean 241-1 2,174,348 9/38 Damond.

2,229,037 1/41 Boldman.

2,454,496 11/48 Ashton 310-2 2,769,929 11/56 Hardway 310-2 2,820,263 1/58 Fruengel.

2,980,345 4/61 Kececioglu 241-1 3,047,169 7/62 Matson 2l464.2

FOREIGN PATENTS 1,230,706 4/60 France.

ANDREW R. J UHASZ, Primary Examiner. 

3. A METHOD FOR SEPARATING LUMPS OF ORE WHICH HAVE BECOME JOINED TOGETHER BY ICE BONDS IN A FROZEN GLOMERATE COMPRISING THE STEPS OF CREATING AN ELECTRICAL CHARGE, DISCHARGING THE ELECTRICAL CHARGE WITHIN A LIQUID MAINTAINED SEPARATE FROM THE GLOMERATE FOR ESTABLISHING A SHOCK WAVE THEREIN, AND TRANSMITTING THE SHOCK WAVE AS A VIBRATIONAL WAVE TO THE GLOMERATE FOR FRACTURING THE ICE BONDS. 